Multiple switch-board



(No Model.)

M. G. KBLLOGG.

MULTIPLE SWITCH BOARD.

No..38`7,889. Patented Aug. 14, 1888.

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IlNiTnn dTaTns taTnNT @einen MIL() G. KELLGGG, OF HYDE BARE, ILLINGIS.

MULTIPLE SWITCH-BOARD.

SPECIFICATION forming` part of Letters Patent No. 387,889, dated August14, 1888.

Application lcd June 6, 1387. Serial Nu/10,418. (No model.)

T0 crZZ whom t may concern,.-

Bc it known that I, MTLo G. KELLOGG, of Hyde Park, Illinois,haveinvented certain new and useful Improvements in Multiple Switch-Boards forTelephone-Exchanges, of which the following is a full, clear,concise, and exact description, reference being had to theaccompanying,` drawings, forming a part of this specification.

lily invention is designed to facilitate the work of switching at thecentral office of a telephone-exchange system; and it consists inmultiple switch-boards for the erchange and independent local circuitsand electric apparatus, wb ereby an operator at any board may readilydetermine whether the line of a subscriber called i'or is in use ateither oi' the other boards, and is adapted to any of the known methodsor combination of methods of sending in the calls or connecting` theterminal stations with or through the central office.

In my system I place as many switch-boards in the central office as arefound necessary or desirable in order to properly answer the calls andconnect and disconnect the subscribers lines. 0n each board I place forcach line which enters the office a switching device or devices adaptedto make the necessary connections and disconnections of the line and tomake the necessary connections and disconnections of the local-testsystem, which I shall hereinafter describe.

In the drawings I have shown spring-jack switches adapted toclosed-circuit lines. Other forms of switches may be nsed which willpractically accomplish the saine purpose. My testing system is alsoapplicable to open-circuit lines, and in this case it is not necessaryto have the switches adapted to remove a ground-connection from a linewhen the line is switched for conversation.

Figures l and ll of the drawings are front views of sections of twomultiple switch-boards to which the same lines are connected. Fig. 2shows a complete diagram ofthe boards with their connections and all thecentral-offline apparatus, circuits, and connections necessary tooperate my test system.

In the drawings like parts and apparatus are indicated by the sameletters of reference.

In Fig. 2, Ais asectional view ofthe switchboard shown in Fig. l, asindicated by line d e,

and A is a sectional view of the switch-board shown in Fig. 1b, asindicated by line c.

c I) represent rubber strips on which the metal parts of the springjackparts are mounted. These strips may be long enongh to receive anyconvenient number of springjaclr parts.

Z Z, die., are rectilinear holes through the fronts and at the edges ofthe strips adapted to receive the switch plugs. The contactsprings g gare mounted to the rear of and are parallel to the holes Z Z to whichthey belong, as shown. The contact-points h h, on which thecontact-springs or spring-levers g y normally bear, pass through thernbberstrips, as shown, and each has a connectingpiece, h', as shown. Acontact-spring, g, and its contactpoint lz. form the main -linecontactpoints of a switch. Toward the front of the switchholes andalong,` their lower faces I place the contact-pieces i fi, as shown.These pieces eX- tend far enough to the front of the holes so that atest-plug or similar device may be applied to any of them by theoperator at the board. In the rear of the contact-pieces i fi, and alsoalong the lower faces of the switchholes, I place the contact-piecesff,as shown. These pieces are normally insulated from all other parts oftheir switches. The contactpiece and the contact-piecef of a switch forma pair of local contact-points, and the contactpiece i also acts as atest-plate or test-bolt of its line.

Fig. 3 shows a switch-plug,` adapted with the switches described above.n is the rubber handle and insulation of the plug. m is the mainlinecontact-piece ofthe plug, to which is connected the iiexibleconductingcord. in is a local contact-piece and is insulated froin m.vi/'hen a plug is inserted into a switch-hole, the piece mpresses ontheleverg and raises it from the contact-point h, and consequentlyconnection is broken between gand 7L and is made between g and in. Atthe saine time the piece in ofthe plug bears on the pieces 'i and f ofthe switch and electrically connects them.

Each section of a rnbberstrip, with its springlever, contact-point,contact-pieces, and the hole, all arranged and operating as above, maybe called a spring -jaclz switch, and the for use switches of a line onthe different boards may be called a series of spring-jack switches. Therubber strips are placed one above the other, as shown. The lower edgeof one strip therefore provides the upper edges ofthe holes in the stripwhich is below it. The holes may be of any convenient arrangementadapted to the shapes and arrangement of the parts used.

Two subscribers lines are sh own in the drawings. They are marked lineNo. 1 and line No. 2. s s are the spring-jack switches for line No. 1 onthe two boards, and r rare the springjack switches of line No. 2 on thetwo boards. The circuits and connections are as follows for the mainlines: Line No. l, for instance, after entering the office, passes firstto spring-lever g of switch s', and thence, through contactpoint h andconnecting-piece 71, of that switch and wire s, to spring-lever g ofswitch s, and thence, through contact-point h and connecting-piece 71,of that switch and wire s, to its calling-annunciator lw, and thence toground. Line N o. 2, as would be every otherline of the exchange, isconnected in a similar manner through its series of switches.

G represents the ground-connection.

E is an electric bell or other test-receiving instrument.

T is a test-plug with a flexible conductingcord,and t is a branchtest-wire for switchboard A, and E is a test-receiving instrument. T isa test-plug with a flexible conductingcord, and t is a branch test-wirefor switchboard A.

B is an electric battery for thelocal test-circuit of line No. l, and Bis a battery for the local test-circuit of line No. 2.

The local test-circuits and connections are as follows: All thecontact-piecesff of all of the switches of the system are connectedtogether. Switches s, s', r, and r are thus shown as having theircontact-pieces f f connected` together by the wire f and its branches ff, &c. All contact-pieces i i, Snc., of the switches of a given line areconnected together. The contact-pieces i and i of switches s and s areshown as connected by Wire 8, and the contact-pieces i and t' ofswitchesrand rare shown as connected by wire 91.

The wire f and its branches may be called the common test-wire,77 andthe wires s"aud its branches, rm and its branches, &c., may be calledindividual test-wires77 of their lines. The test-battery of a line isplaced in a loop or wire which connects the common test-wire with theindividual test-wire of the line. This Wire may be considered as a partof the individual test-wire, and the wires to the pieces 'L' i of itsswitches should not branch off between the battery and the commontest-wire.

The branch testwire of a switch -board branches off from the commontest-wire, as shown, and in it is placed the test-receiving instrument.It terminates in the test-plug T or T', with its flexible cord adaptedto be brought at will into connection with any contact-piece i of itsboard. These branch wires :may terminate in or be connected to any othercircuit from her test-plug through her testbell, thence th rough thecommon test-wire to the individual. test-wire of the line and thebattery, and thence to the contact-piece 1'- thus forming a closedcircuit in which is the bell and the battery. If, however, the line isswitched at another board, the bell will not ring, because the batteryis short-circuited by a circuit of very much smaller resistance throughthe contact-piece m of the switchplug which is used to switch the liucand the circuits, as shown and described. The operator will thus know ontesting whether or not the line is switched for use at another board.

I have only shown two switch-boards in use and two test-bells-onetest-bell for each board. Other switch-boards and other test-bells mightbe added to the system and the connections of the lines and switches andtest-circuits would be similar to the above, and such as will be evidentto those skilled in the art.

I have not shown in detail the method of answering calls and makingconnections at the central ottice. Vell-known forms of apparatus andconnections may be used for this purpose.

I claim as my invention and desire to secure by Letters Patent- 1. In atelephone-exchange system, two or more multiple switch-boards to whichthe same telephone-lines are connected, local testcircuits havingapairof contact-points or testbolts at the switches, one test-circuit foreach line, each test-circuit containing a battery and connected to eachboard on each side of the battery, and said battery being normally open,and a switch-plug having insulated contacts crossing the test-bolts atthe connected switches for automatically shunting the test-circuitaround a tested switch through a line of less resistance when the mainline is switched for conversation at another switch, in combination witha test-receiving instrument connected on one side to each test-circuitat one side of the battery, and a test-plug whereby the operator may atwill connect the test-receiving instrument on its other side to anytest-circuit at the other side of the battery, substantially as and forthe purpose set forth.

2. In a telephoneexchange syste1n,the combination of two or moremultiple switch-boards for telephone-lines with series of switches, oneswitch for each telephone-line, and one switch of each series being oneach board, circuitclosers, one circuit-closer for each switch,eachcircuit-closer being closed automatically by the insertion of a plug inits switch, local test- IOO IIO

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circuits, each test-circuit containing a testbattery and twocontact-pieces and connected on the two sides of its battery to the twocontact-pieces, respectively, of each of its circuitclosers on theseveral boards, a test-receiving instrument at each board, andswitch-testing devices whereby the operator at any board may at willconnect her test-receiving instrunient into circuit with either of saidtest-circuits, the connection with said circuit being on the two sidesof its test-battery, substantially as and for the purpose set forth.

3. In a telephone-line switch, the combination of the main-line contactsg and 7L, a pair of contactpoints which are closed on the insertion of aswitch-plug and opened on its withdrawal,said contact-points beingmounted on one of the inner faces of the plughole and insulated from thecontacts g and It, and one of said contact-points being also a testplatefor the line to which a test-plug may be applied, substantially as setforth.

4. A spring-jack switch containing within the plughole two main-linecontact points or pieces which are normally in contact with each other,in combination with apair of test-bolts arranged within the plug-ho1e onone of the inner faces of the plug-hole and insulated 'from each otherand from the mainline contact-pieces, and a switclrplug` having twoparallel insulated contact-pieces, said plug being adapted, wheninsertedinto the switch, to dis connect the main-line contact-pieces from eachother and connect one of them to one of the contact-pieces on the plugand to cross the two test-bolts through the other contactpiece of theplug, substantially as set forth.

5. In a telephone-exchange system, multiple switch-boards provided withseries of switches, one switch for each telephoneline, and one switchfor each series arranged on each board, local-circuit closers, onecircuit-closer for each switch, and each comprising separate contacts,whereby it is closed automatically by the in sertion of a switch-pluginto its switch, testplates arranged one for each switch, each testiplate being one of the contact-points of the circuit-closer of itsswitch, or connected thereto, local test-circuits, one for each line,each test-circuit containing a test-battery and connected on the twosides of its battery to the two contact-pieces, respectively, of each ofits circuit-closers on the several boards, a test-receiving instrumentat each board, and a plug for each test-receiving instrument, said plugbeingconnectcd with a lexible conductingcord to one side of thetest-receiving instrument and adapted at the will of the operator to bebrought into connection with any of the test-plates at her board, andthe test-receiving instruments being connected on their other side withsaid `local test-circuits with their batteries between the instrumentsand their test-plates, substantially as and for the purpose set forth.

6. In a telephone-exchange system, thecombinationof'twoormoreswitch-boards,the main lines andniai n-linecircuits between the boards, the test-circuits, one for each line,including all the boards, a battery in every test-circuit, a commontest-wire connected with all the testcircuits, test devices connectedwith said common test-wire, and test-bolts at each switch included inthe test-circuits, substantially as set forth.

7. In a telephone-exchange system, the combination of test-circuits, thetest-bolts at each switch connected with the test-circuit, a testplugconnected with a signaling` device and with all the test-circuits at oneend and adapted to close a circuit through the signaling device when theline is not switched, and circuit-coa nections of comparatively lowresistance between the test-circuits at one board with the test-bolts atthe other boards, whereby the testcircuit at the tested board isshort-circuited when the line is switched at another board.

8. In a telephone-exchange system, the con1- bination of thecontact-pieces f f at the several switches, the common test-wire f andbranches f2, which connect them, the contactpieces i at the severalswitches, electrical connections between all the pieces t in a givenline, a battery in each test-circuit, and a test plug and signal,substantially as set forth.

MIL() G. KELLOG G.

Witnesses:

CALVIN DE WOLF, WALLACE L. DE WOLF.

